It's just a trick, I took a base texture and removed the space around the bricks. Then I layered these bricks on top of the base texture each distanced 0.1 game units from another. These layers look 3D in-game.

It would affect the performance but I'm not sure how much, these tests have 8x times more polygons per face but maybe that's too much detail for something as shallow as a brick wall, could have easily gone with 2 layers here.
Probably cheaper than actual paralax mapping.

Since a larger amount of textures needs to be used this would affect the map size greatly.

I had this idea a long time ago, just wanted to see how it would look.